[linux-cirrus] Re: Memory mapping (virtual to physical) __virt_to_phys()
- From: NZG <ngustavson@xxxxxxxxxxx>
- To: linux-cirrus@xxxxxxxxxxxxx
- Date: Mon, 18 Jun 2007 10:04:15 -0500
I've seen the same thing,
I believe the standard __virt_to_phys macro's don't work because mmaping is
being setup outside of the standard Linux method in:
include/asm-arm/arch-ep93xx/ep93xx-regs.h
Your path of least resistance is probably to use those macro's instead for
standard register mappings.
gl,
NZG
> -----Original Message-----
> From: linux-cirrus-bounce@xxxxxxxxxxxxx
> [mailto:linux-cirrus-bounce@xxxxxxxxxxxxx] On Behalf Of Wagner Scott
> (ST-IN/ENG1.1)
> Sent: Monday, June 18, 2007 9:09 AM
> To: linux-cirrus@xxxxxxxxxxxxx
> Subject: [linux-cirrus] Memory mapping (virtual to physical)
> __virt_to_phys()
>
>
> Hello all,
>
> I have an EP9302 running Linux 2.6.14 and using the following memory
> mapping:
> * 0xF200_0000 - 0xF2FF_FFFF 16 MB 0xfebfc000 nCS0 NAND
> Flash Address
> * 0xF100_0000 - 0xF1FF_FFFF 16 MB 0xfebfb000 nCS0 NAND
> Flash Command
> * 0xF000_0000 - 0xF0FF_FFFF 16 MB 0xfebfa000 nCS0 NAND
> Flash Data
> * 0xE000_0000 - 0xEFFF_FFFF 256 MB 0xc8000000 nSDCS2 SDRAM #2
> * 0xD000_0000 - 0xDFFF_FFFF 256 MB - nSDCS1 Unused
> * 0xC000_0000 - 0xCFFF_FFFF 256 MB - nSDCS0 Unused
> * 0x8080_0000 - 0x8FFF_FFFF 248 MB 0xE0800000 APB EP9302
> Peripherals
> * 0x8000_0000 - 0x800F_FFFF 1 MB 0xE0000000 AHB EP9302
> Peripherals
> * 0x7000_0000 - 0x7FFF_FFFF 256 MB - nCS7 Unused
> * 0x6000_0000 - 0x6FFF_FFFF 256 MB - nCS6 Unused
> * 0x4000_0000 - 0x4FFF_FFFF Unused
> * 0x3000_0000 - 0x3000_00FF 256 B 0xfebf3000 nCS3
> Peripheral 3
> * 0x2000_0000 - 0x2000_00FF 256 B 0xfebf2000 nCS2
> Peripheral 2
> * 0x1000_0000 - 0x1000_00FF 256 B 0xfebf0000 nCS1
> Peripheral 1
> * 0x0000_0000 - 0x0FFF_FFFF 256 MB 0xc0000000 nSDCS3 SDRAM #1
>
> My problem is with the __virt_to_phys() macro in
> ./include/arch/arm/memory.h. I have __phys_to_virt() mapping SDRAM
> physical addresses 0x00nn_nnnn to vrtual 0xC0nn_nnnn for the low block;
> 0xE0nn_nnnn to 0xC8nn_nnnn for the low block. I would expect that
> __virt_to_phys() should map addresses 0xC0nn_nnnn to 0x00nn_nnnn for the
> low block; 0xC8nn_nnnn to 0xE0nn_nnnn for the low block.
>
> This does not do what I expect. When I use this __virt_to_phys() mapping,
> the EP9302 peripherals do not work (note that they are mapped at virtual
> address 0xE0nn_nnnn). If I have __virt_to_phys() map the high block at
> C800_0000 to 4000_0000 (where there is nothing in either virtual or
> physical space), everything seems to work OK.
>
> I don't understand this. First, why can't I do a V to P mapping back to
> E0x? The peripherals are at _virtual_ E0, not _physical_ E0. Second, why
> does lying and mapping the high SDRAM block back to 40x (where there is
> absolutely nothing) work?
>
> Thanks in advance.
>
> Scott Wagner
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